I'm using Opera on a Windows tablet, and need to use a SOCKS5 proxy. I can set the proxy either using an addon (for example, "SimpleProxy") or by adding command-line switches, and it works fine on some sites, however on some other sites, for example www.google.com, these symptoms occur:

(Note: I'm using a localized version of Opera, so the text below may not be exact)

• I type the address into the address bar and press Enter
• The circle spins, the status popup at bottom left reads "sending request to <site>..." for a long time, maybe a minute or so
• An error page is shown, saying "Cannot access this website, <site> is taking too long to respond", however the circle is still spinning and the status popup is still there, and it stays like this for another minute or so
• Finally the site loads

Why does this happen? Is there something I can do to troubleshoot this behavior?